I consider breathing very important in martial arts. It recovers you with fresh air when you inhale, it prevents being knocked down easily by the punch or kick in the diaphragm, it helps you make a good rhythm in fight, it helps you to be faster and more explosive, etc. There are so many benefits of good and different breathing in the martial arts that it is a great subject to talk about. Kiai is also special kind of breathing and there are many benefits from it as well. With Kiai, you bring the most out of yourself on training and in battle. The least important is how it sounds but what it gives to you. The best way is to find it naturally. Putting the most Energy and power in your punches and kicks in training makes your training harder and gives you definitive path towards crossing your borders. Also you learn how to control yourself and you will not use it often in a fight, but when you need it for finishing blows, when you train it regularly you will know how and when to use it. If you don't train in that way it is hard for you to use it when is needed because your body has no knowledge of it and it did not become natural. It can be embarrassing for some people to use it but you need to be free in your mind, without prejudice and to alow yourself to learn different kind of stuff, at the end you decide what kind of weapon you will take to the battle but first you must have all the needed weapons at yourself. I consider trained Kiai as one of such great weapons that you use only one or few times in a fight.
P.S. About the "GOATMAN", I think that he has good Kiai, but he cannot use it in a proper way because he has his mouth piece in his mouth. In that situation every single one of us would sound like a goat. So, please, don't rush so easily into a conclusions and please stop giving nicknames before you have all needed information, it is not in a spirit of true and sincere martial artists.
Kindest regards to you all!
OSU!
Sensei Žarko Dukić